824  
FXUS63 KLSX 090232  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
932 PM CDT TUE JUL 8 2025  
   
KEY MESSAGES  
 
- SCATTERED THUNDERSTORMS ARE EXPECTED TO TRACK SOUTHEAST THROUGH  
THE REGION TODAY. A FEW THUNDERSTORMS COULD BE STRONG, INCLUDING  
THE POTENTIAL FOR ISOLATED SEVERE THUNDERSTORMS WITH WINDS GUSTS  
TO 60 MPH AND LOCALLY HEAVY RAIN.  
 
- WARM, SEASONABLE TEMPERATURES WILL PERSIST THROUGH THE NEXT  
SEVERAL DAYS ALONG WITH PERIODIC CHANCES FOR THUNDERSTORMS TO  
IMPACT THE REGION.  
 
 
   
SHORT TERM  
(THROUGH LATE WEDNESDAY NIGHT)  
ISSUED AT 138 PM CDT TUE JUL 8 2025  
 
THUNDERSTORM POTENTIAL WILL BE THE PRIMARY FOCUS THIS AFTERNOON  
INTO THIS EVENING AS AN UPPER LEVEL TROUGH AND MCV (MESOSCALE  
CONVECTIVE VORTEX) ROTATE SOUTHEASTWARD THROUGH LATE THIS EVENING.  
IR SATELLITE SHOWS A BROAD EXPANSE OF BROKEN/OVERCAST CLOUDS  
EXTENDING FROM NORTHERN MO THROUGH PORTIONS OF IA/IL/WI. CLOUDS  
ARE ASSOCIATED WITH THE MCV, REMNANT OF A CONVECTIVE COMPLEX THAT  
DEVELOPED OVER SD/NE LAST EVENING. ANOTHER AREA OF CLOUDS AND  
CONVECTION EXTEND FROM EASTERN OK INTO SOUTHERN IN. IN BETWEEN THE  
TWO AREAS, SKIES HAVE REMAINED MOSTLY CLEAR, ALLOWING INSTABILITY  
TO BUILD AHEAD OF THE APPROACHING MCV.  
 
AS OF 18Z, SPC MESOANALYSIS SHOWS A WHAT LITTLE CIN THAT EXISTS  
EXTENDING FROM KANSAS CITY ROUGHLY JUST WEST OF QUINCY, IL. WHERE  
SKIES HAVE REMAINED MOSTLY CLEAR, SURFACE INSTABILITY HAS CLIMBED  
WITH 2500 J/KG OF SBCAPE ROUGHLY ALONG AND NORTH OF THE I-44  
CORRIDOR INTO SOUTHWESTERN IL ALONG I-70. THIS NOT ONLY JIVES  
PRETTY WELL WITH GUIDANCE FROM PRIOR RUNS, INCLUDING THIS MORNING,  
AND MAYBE EVEN ON THE HIGHER END. HREF MEANS SHOWED SBCAPE OF  
2-2.2K WITH DETERMINISTIC HI-RESE GUIDANCE (RAP/HRRR) PLOTTING  
2.5-3K THIS AFTERNOON. MOISTURE IS NO QUESTION WITH DEWPOINTS IN  
THE UPPER 60S TO LOW-70S AND PWATS AROUND 1.7" PER SPC  
MESOANALYSIS. THUNDERSTORMS WILL CERTAINLY HAVE THE MOISTURE TO  
PRODUCE EFFICIENT RAINFALL WITH LOCALLY HEAVY RAIN, RESULTING IN  
PONDING/NUISANCE FLOOD IN AREAS IMPACTED BY MULTIPLE CELLS. THOUGH  
SOUNDINGS AREN'T SHOWING A PARTICULARLY CLASSIC INVERTED-V,  
50-100MB DEWPOINT DEPRESSIONS IN THE REALM OF 10-13C SUGGEST  
LOCALIZED DOWNBURSTS WITH MARGINALLY SEVERE WIND GUSTS (60 MPH)  
ARE POSSIBLE. HAIL CANNOT BE ENTIRELY RULED OUT, BUT WHAT DOES  
FALL IS LIKELY SUB-SEVERE WITH MID-LEVEL LAPSE RATES AT 5.5-6C AND  
COMPETING UPDRAFTS AS SCATTERED CONVECTION BECOME MORE NUMEROUS  
IN TIME.  
 
DESPITE SOME SLIGHT SPATIAL/TEMPORAL VARIABILITY BETWEEN  
DETERMINISTIC HI-RES MODELS, PAINTBALL PLOTS (SIMULATED REFLECTIVITY  
>40 DBZ) SHOW A GENERAL CONSENSUS THAT THE BEST TIMEFRAME FOR  
DEVELOPMENT RUNS FROM NEAR KCOU TO JUST SOUTH OF KPPQ. IR SATELLITE  
IS SHOWING A NOTABLE UPTICK IN DEVELOPMENT IN THIS REGION,  
INCREASING CONFIDENCE THAT THIS WILL BE THE REGION FOR FOCUSED  
INITIATION. THUNDERSTORMS THEN MOVE SOUTHEAST THROUGH APPROXIMATELY  
8-9 P.M. AS THUNDERSTORMS PROGRESS SOUTHEAST AND WEAKEN AFTER  
SUNSET.  
 
ONCE THUNDERSTORMS CLEAR TO THE SOUTHEAST AND DISSIPATE LATE THIS  
EVENING, CLOUDS LIKELY HANG ON FOR SOME TIME TONIGHT BEFORE PARTIAL  
CLEARING WORKS INTO NORTHEAST MO. THERE IS SOME HINT AT PATCHY FOG  
DEVELOPMENT RUNNING FROM CENTRAL TO NORTHEAST MO, BUT CLOUD COVER  
MAY NOT CLEAR QUICK ENOUGH BEFORE SUNRISE, LIMITING FOG POTENTIAL.  
THIS WILL BE SOMETHING TO MONITOR THROUGH TONIGHT, BUT EVEN IF FOG  
DEVELOPS, IT IS NOT EXPECTED TO BE ANYTHING SIGNIFICANT WITH THE  
LIMITED TIME TO TAKE ADVANTAGE OF CLEARING.  
 
BY WEDNESDAY, MOSTLY DRY CONDITIONS ARE EXPECTED WITH THE LOW CHANCE  
THAT AN ISOLATED SHOWER MAY DEVELOP. HOWEVER, MUCH OF THE POTENTIAL  
WILL RESIDE OUTSIDE THE CWA. SHOULD ANYTHING DEVELOP, THE BEST  
CHANCE (30-40%) WILL LINE UP ALONG THE SOUTHEAST PORTION OF THE CWA  
WITH CHANCES QUICKLY TAPERING TO THE NORTH AND DROPPING THROUGH THE  
DAY AS SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTHWEST.  
 
MAPLES  
 
 
   
LONG TERM  
(THURSDAY THROUGH NEXT TUESDAY)  
ISSUED AT 248 PM CDT TUE JUL 8 2025  
 
ENSEMBLES AND NBM GUIDANCE SHOW A PERSISTENT, SEASONABLY WARM  
PATTERN WITH RELATIVELY SMALL SPREAD THROUGH THE EXTENDED RANGE.  
VARIABILITY IS GREATEST ON DAYS WITH BETTER CONVECTIVE POTENTIAL  
AND EVEN THEN, SPREAD IS CONSIDERABLY SMALL IN COMPARISON TO  
EVENTS INVOLVING WHOLESALE CHANGE.  
 
THE UPPER LEVEL RIDGE CENTERED OVER THE DESERT SOUTHWEST IS  
EXPECTED TO FLATTEN AND SHIFT WESTWARD OVER SOUTHERN CA AND THE  
BAJA PENINSULA BY THURSDAY. THIS RESULTS IN SOUTHWARD SHIFT IN THE  
ACTIVE 500MB VORT TRACK THAT HAS KEPT THE NORTHERN CONUS ACTIVE  
OVER THE LAST SEVERAL DAYS. SEVERAL SHORTWAVES CONTINUE TO ROUND  
THE NORTHERN PERIPHERY OF THE RIDGE, PROGRESSING WEST TO EAST  
OVER THE INTERMOUNTAIN WEST INTO THE CENTRAL PLAINS AND MID-  
MISSISSIPPI VALLEY. THOUGH THIS LOOKS LIKE AN OPPORTUNITY FOR  
MULTIPLE, PERIODIC ROUNDS OF CONVECTIVE POTENTIAL, SURFACE  
FEATURES AND TIMING WILL BE KEY IN THE MAGNITUDE AND SPREAD OF  
ACTIVITY.  
 
SURFACE HIGH PRESSURE MOVES INTO THE GREAT LAKES BUT MAINTAINS  
SOME INFLUENCE EARLY THURSDAY AS THE FIRST SUCH SHORTWAVE TRACKS  
NEAR THE IA/MO BORDER. THIS LOOKS PRETTY CLOSE TO SCENARIOS WE'VE  
SEEN PAN OUT OVER THE LAST COUPLE OF DAYS WITH AFTERNOON/EVENING  
CONVECTION INITIALIZING TO THE NORTH AND TRACKING SOUTHEASTWARD AT  
THE EASTERN PERIPHERY OF THE UPPER RIDGE. HOWEVER, THIS ROUND  
FORMS AT THE NOSE OF A 40-45 KNOT LOW LEVEL JET THAT SET UP OVER  
THE CENTRAL PLAINS. DETERMINISTIC GUIDANCE (ECM/GFS) IS FAIRLY  
GOOD AGREEMENT WITH THE PLACEMENT OF THIS SYSTEM AT THIS TIME,  
WHICH WOULD HAVE CONVECTIVE TRENDS MOVING SOMEWHERE ALONG THE MS  
RIVER VALLEY INTO MO/IL THURSDAY MORNING. USUALLY CONVECTIVE  
COMPLEXES OF THIS NATURE WILL WEAKEN AS THE LOW LEVEL JET FADES  
THROUGH THE DAY AND THE COMPLEX BECOME OUTFLOW DOMINANT.  
NONETHELESS, IT MAY BE SOMETHING TO WATCH SHOULD TIMING/PLACEMENT  
SHIFT OVER THE NEXT COUPLE OF DAYS. CHANCES FOR SHOWERS AND  
THUNDERSTORMS ARE MOST FAVORED OVER NORTHEASTERN MO AND WEST-  
CENTRAL IL IN THIS SCENARIO, AS CONVECTION WOULD TEND TO WEAKEN  
THROUGH THE MORNING/EARLY AFTERNOON (IF IT LASTS THAT LONG).  
 
FRIDAY LARGELY LOOKS DRY AS WE AWAIT THE NEXT UPTICK IN  
THUNDERSTORM POTENTIAL, WHICH MAY BE THE BEST SHOT OVER THE COURSE  
OF THE WEEK. THIS WILL COME IN THE FORM OF A DEEPER TROUGH THAT  
CLOSELY FOLLOWS THURSDAY'S LEAD SHORTWAVE. THIS SHORTWAVE GIVE  
RISE TAKE ON A SLIGHT NEGATIVE TILT AHEAD OF AN AMPLIFIED,  
POSITIVELY TILTED TROUGH THAT EXTENDS SOUTHWESTWARD INTO THE  
NORTHERN PLAINS. AS THE SHORTWAVE APPROACHED, THE SURFACE LOW IS  
EJECTED NORTHEAST THROUGH THE CENTRAL PLAINS INTO THE UPPER  
MIDWEST. A COLD FRONT THAT TRAILS THE SYSTEM SLOW PUSHES SOUTHEAST  
LATE FRIDAY INTO EARLY SATURDAY. WHILE THIS MAY BE THE BEST  
OPPORTUNITY FOR RAINFALL PROVIDED SURFACE CONVERGENCE UNDERNEATH  
MID/UPPER ASCENT, WHERE THE SYSTEM TRACK AND WHEN IT MOVES THROUGH  
WILL PLAY A HUGE ROLE IN PRECIPITATION POTENTIAL. IF THE UPPER  
TROUGH AND SHORTWAVE TRACK TOO FAR NORTH, THIS WOULD PLACE THE  
MID- MISSISSIPPI RIVER VALLEY IN TERRITORY IN WHICH THE COLD FRONT  
RELIES ON DIURNAL INSTABILITY AND CONVERGENCE. WHILE DIURNAL  
CONVECTION WOULD RESULT IN BENEFICIAL RAINFALL, THUNDERSTORMS  
POTENTIAL WOULD STRUGGLE TO SURVIVE THROUGH THE DIURNAL LULL.  
 
THEREFORE, WHILE THERE ARE MULTIPLE OPPORTUNITIES FOR RAINFALL,  
THERE ARE ENOUGH CAVEATS TO QUESTIONS JUST HOW MUCH OF IT WILL  
COME TO FRUITION TO BENEFIT THE REGION WITH WIDESPREAD POTENTIAL.  
 
MAPLES  
 
 
   
AVIATION  
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)  
ISSUED AT 932 PM CDT TUE JUL 8 2025  
 
THE MAIN CONCERN FOR OVERNIGHT IS FOG POTENTIAL. CONTINUE TO THINK  
THAT THE BEST CHANCES ARE IN CENTRAL MISSOURI AS BOTH KCOU/KJEF  
DID RECEIVE SOME RAIN AND AT LEAST SOME PARTIAL CLEARING IS LIKELY  
OVERNIGHT. IFR VISIBILITIES ARE EXPECTED AT BOTH OF THESE  
TERMINALS LATE TONIGHT INTO EARLY WEDNESDAY MORNING. ELSEWHERE,  
THE FOG POTENTIAL IS A LOWER DUE TO LINGERING CLOUD COVER. KSUS  
MAY AT LEAST HAVE A BRIEF PERIOD OF MVFR VISIBILITES AS SOME LATE  
PARTIAL CLEARING IS EXPECTED BEFORE DAYBREAK.  
 
ANY FOG SHOULD QUICKLY LIFT/DISSIPATE BY 1300 UTC, WITH DRY/VFR  
CONDITIONS AND LIGHT/VARIABLE WINDS EXPECTED THROUGH WEDNESDAY  
EVENING. CANNOT COMPLETELY RULE OUT A ROGUE SHOWER/WEAK  
THUNDERSTORM ON WEDNESDAY AFTERNOON, BUT THE COVERAGE CONTINUES TO  
LOOK MUCH TOO LOW TO ADD ANY VC OR PROB30 MENTION TO ANY OF THE  
TERMINALS AT THIS JUNCTURE.  
 
GOSSELIN  
 
 
   
LSX WATCHES/WARNINGS/ADVISORIES  
 
MO...NONE.  
IL...NONE.  
 
 
 
 
WFO LSX  
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